Field of Invention
The present invention relates to a package structure and a manufacturing method thereof.
Description of Related Art
With the development of package structures, low cost redistribution layers and bumping technologies have been progressively improved. A passivation layer made of polyimide (PI) provides a good buffer to bumps disposed thereon with its elasticity. However, the PI layer has low adhesive strength to its underlying and overlying layers, and the PI layer may be easily peeled off from a wafer and cause damage to its end product structure. On the other hand, since the PI layer may shrink during processing, the quality of the end product, such as pitch, may be affected accordingly.
A passivation layer made of hard material, such as SiO2, may provide good forming accuracy and fine-pitch. However, this type of layer may induce high inner stress in a region under bumps and may cause damage to the overall structure accordingly. Thus, for meeting requirements for good pitch quality and high reliability, advanced package forming methods and structures are needed.